The present review focuses on summarizing key advances made on controlling polymer blend morphology to improve electrical conductivity in carbon-based polymer composite materials, including those based on carbon black, carbon nanotubes, and graphene. Fundamentals for controlling polymer morphology and the distribution of conductive fillers in various polymer composite systems and the impact on the electrical, rheological, mechanical, and thermal properties are reviewed. The concept of triple percolation and its beneficial effect on electrical conductivity is then reviewed.

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Multiphase polymer blends provide unique morphologies to reduce the percolation concentration and increase conductivity of carbon-based polymer composites via selective distribution of the conductive filler. In this work, the kinetic and thermodynamic effects on a series of multiphase conductive polymer composites were investigated. The electrical conductivity of carbon black (CB)-filled conductive polymer blend composites comprising polypropylene, poly(methyl methacrylate), and ethylene-acrylic acid were determined as a function of compounding sequence and annealing time. Kinetic and thermodynamic parameters were found to influence the conductivity. Phase morphology and conductivity at short annealing times were influenced by the compounding sequence where the CB was added after being premixed with one of the polymer components or directly added to the threecomponent polymer melt. However, they were thermodynamically driven at longer annealing times; the resistivity was found to decrease by a statistically significant amount to similar levels for all the composite systems with increasing annealing time. The increase in conductivity at longer annealing times was determined to be the result of changes in the phase morphology from seaisland, dispersed microstructure to a tri-continuous morphology rather than change in localization of CB, given that the CB was found to be entirely located in the EAA phase even at short annealing times (and independent of compounding sequence), where the conductivity was not measurable.